
fn new_expr(type_: i32, parameters: Option<&[*const TEExpr]>) -> *mut TEExpr {
    let arity = unsafe { ARITY(type_) };
    let psize = mem::size_of::<*const TEExpr>() * arity as usize;
    let size = (mem::size_of::<TEExpr>() - mem::size_of::<*const TEExpr>())
        + psize
        + if unsafe { IS_CLOSURE(type_) } {
            mem::size_of::<c_void>()
        } else {
            0
        };
    let ret = unsafe { malloc(size) as *mut TEExpr };
    if ret.is_null() {
        eprintln!("Out of memory");
        std::process::exit(1);
    }
    unsafe {
        ptr::write_bytes(ret, 0, size);
        if let Some(params) = parameters {
            ptr::copy_nonoverlapping(
                params.as_ptr(),
                (*ret).parameters.as_mut_ptr(),
                arity as usize,
            );
        }
        (*ret).type_ = type_;
        (*ret).bound = 0;
    }
    ret
}

 fn handle_enum(some_enum: SomeEnum) {
     match some_enum {
  match some_enum {
      SomeEnum::Variant1 => {
          println!("It's Variant 1");
      }
      SomeEnum::Variant2 => {
          println!("It's Variant 2");
          if some_condition {
               println!("Condition met for Variant 2");
           }
      }
  }
 }
   
   fn main() {
       // Some main function code
   }
fn te_free(n: *mut te_expr) {
    if n.is_null() {
        return;
    }
    te_free_parameters(n);
    unsafe {
        libc::free(n as *mut libc::c_void);
    }
}

fn fac(a: f64) -> f64 {
    if a < 0.0 {
        return f64::NAN;
    }
    if a > u32::MAX as f64 {
        return f64::INFINITY;
    }
    let ua = a as u32;
    let mut result: u64 = 1;
    for i in 1..=ua {
        if i > (u64::MAX / result) as u32 {
            return f64::INFINITY;
        }
        result *= i as u64;
    }
    result as f64
}

fn ncr(n: f64, r: f64) -> f64 {
    if n < 0.0 || r < 0.0 || n < r {
        return f64::NAN;
    }
    if n > u32::MAX as f64 || r > u32::MAX as f64 {
        return f64::INFINITY;
    }
    let un = n as u64;
    let mut ur = r as u64;
    let mut result: u64 = 1;
    if ur > un / 2 {
        ur = un - ur;
    }
    for i in 1..=ur {
        if result > u64::MAX / (un - ur + i) {
            return f64::INFINITY;
        }
        result *= un - ur + i;
        result /= i;
    }
    result as f64
}

fn find_builtin(name: &str, len: usize) -> Option<&te_variable> {
    let mut imin = 0;
    let mut imax = FUNCTIONS.len() as isize - 2;
    while imax >= imin {
        let i = imin + (imax - imin) / 2;
        let func_name = &FUNCTIONS[i as usize].name;
        let c = match name.get(..len).unwrap_or("").cmp(&func_name[..len]) {
            std::cmp::Ordering::Equal => "\0".cmp(&func_name[len..]),
            other => other,
        };
        if c == std::cmp::Ordering::Equal {
            return Some(&FUNCTIONS[i as usize]);
        } else if c == std::cmp::Ordering::Greater {
            imin = i + 1;
        } else {
            imax = i - 1;
        }
    }
    None
}

 fn find_lookup<'a>(s: &'a State, name: &'a str, len: usize) -> Option<&'a TeVariable> {
     if s.lookup.is_none() {
         return None;
    }
    let lookup = s.lookup.as_ref().unwrap();
    let lookup_len = s.lookup_len as usize;
    for var in lookup.iter().take(lookup_len) {
        if name[..len] == var.name[..len] && var.name.as_bytes()[len] == 0 {
            return Some(var);
        }
    }
    return None;
}

fn next_token(s: &mut State) {
    s.tok_type = TokType::TokNull;
    loop {
        if s.next.is_empty() {
            s.tok_type = TokType::TokEnd;
            return;
        }
        let first_char = s.next.chars().next().unwrap();
        if first_char.is_digit(10) || first_char == '.' {
            let parsed_value: f64 = s.next.parse().unwrap_or_default();
            s.value = parsed_value;
            s.next = "";
            s.tok_type = TokType::TokNumber;
        } else if first_char.is_alphabetic() {
            let start = s.next;
            let mut end_pos = 0;
            for (i, ch) in s.next.chars().enumerate() {
                if ch.is_alphabetic() || ch.is_digit(10) || ch == '_' {
                    end_pos = i + 1;
                } else {
                    break;
                }
            }
            s.next = &s.next[end_pos..];
            let var = find_lookup(s, start, end_pos).or_else(|| find_builtin(start, end_pos));
            if var.is_none() {
                s.tok_type = TokType::TokError;
            } else {
                match type_mask(var.unwrap().vtype) {
                    VarType::TEVariable => {
                        s.tok_type = TokType::TokVariable;
                        s.bound = var.unwrap().address;
                    }
                    VarType::TEClosure0
                    | VarType::TEClosure1
                    | VarType::TEClosure2
                    | VarType::TEClosure3
                    | VarType::TEClosure4
                    | VarType::TEClosure5
                    | VarType::TEClosure6
                    | VarType::TEClosure7 => {
                        s.context = var.unwrap().context;
                        s.tok_type = var.unwrap().vtype;
                        s.function = Some(var.unwrap().address);
                    }
                    VarType::TEFunction0
                    | VarType::TEFunction1
                    | VarType::TEFunction2
                    | VarType::TEFunction3
                    | VarType::TEFunction4
                    | VarType::TEFunction5
                    | VarType::TEFunction6
                    | VarType::TEFunction7 => {
                        s.tok_type = var.unwrap().vtype;
                        s.function = Some(var.unwrap().address);
                    }
                    _ => s.tok_type = TokType::TokError,
                }
            }
        } else {
            s.tok_type = match first_char {
                '+' => TokType::TokInfix { function: add },
                '-' => TokType::TokInfix { function: sub },
                '*' => TokType::TokInfix { function: mul },
                '/' => TokType::TokInfix { function: divide },
                '^' => TokType::TokInfix { function: pow },
                '%' => TokType::TokInfix { function: fmod },
                '(' => TokType::TokOpen,
                ')' => TokType::TokClose,
                ',' => TokType::TokSep,
                ' ' | '\t' | '\n' | '\r' => TokType::TokNull,
                _ => TokType::TokError,
            };
            if s.tok_type != TokType::TokNull {
                s.next = &s.next[1..];
            }
        }
        if s.tok_type != TokType::TokNull {
            break;
        }
    }
}

fn base(s: &mut state) -> *mut te_expr {
    let mut ret: *mut te_expr;
    let mut arity: i32;
    match TYPE_MASK(s.type_) {
        TOK_NUMBER => {
            ret = new_expr(TE_CONSTANT, 0);
            CHECK_NULL(ret);
            unsafe {
                (*ret).value = s.value;
            }
            next_token(s);
        }
        TOK_VARIABLE => {
            ret = new_expr(TE_VARIABLE, 0);
            CHECK_NULL(ret);
            unsafe {
                (*ret).bound = s.bound;
            }
            next_token(s);
        }
         Type::TE_FUNCTION0 | Type::TE_CLOSURE0 => {
             ret = new_expr(s.type_, 0);
             CHECK_NULL(ret);
            unsafe {
                (*ret).function = s.function;
                if IS_CLOSURE(s.type_) {
                    (*ret).parameters[0] = s.context;
                }
            }
            next_token(s);
            if s.type_ == TOK_OPEN {
                next_token(s);
                if s.type_ != TOK_CLOSE {
                    s.type_ = TOK_ERROR;
                } else {
                    next_token(s);
                }
            }
        }
          Type::TE_FUNCTION1 | Type::TE_CLOSURE1 => {
              ret = new_expr(s.type_, 0);
             CHECK_NULL(ret);
             unsafe {
                 (*ret).function = s.function;
                 if IS_CLOSURE(s.type_) {
                     (*ret).parameters[1] = s.context;
                 }
             }
             next_token(s);
             unsafe {
                 (*ret).parameters[0] = power(s);
                 CHECK_NULL((*ret).parameters[0]);
             }
         }
         Type::TE_FUNCTION2 | Type::TE_FUNCTION3 | Type::TE_FUNCTION4 | Type::TE_FUNCTION5 | Type::TE_FUNCTION6 | Type::TE_FUNCTION7
         | Type::TE_CLOSURE2 | Type::TE_CLOSURE3 | Type::TE_CLOSURE4 | Type::TE_CLOSURE5 | Type::TE_CLOSURE6 | Type::TE_CLOSURE7 => {
            arity = ARITY(s.type_);
            ret = new_expr(s.type_, 0);
            CHECK_NULL(ret);
            unsafe {
                (*ret).function = s.function;
                if IS_CLOSURE(s.type_) {
                    (*ret).parameters[arity as usize] = s.context;
                }
            }
            next_token(s);
            if s.type_ != TOK_OPEN {
                s.type_ = TOK_ERROR;
            } else {
                let mut i: i32 = 0;
                while i < arity {
                    next_token(s);
                    unsafe {
                        (*ret).parameters[i as usize] = expr(s);
                        CHECK_NULL((*ret).parameters[i as usize]);
                    }
                    if s.type_ != TOK_SEP {
                        break;
                    }
                }
                if s.type_ != TOK_CLOSE || i != arity - 1 {
                    s.type_ = TOK_ERROR;
                } else {
                    next_token(s);
                }
            }
        }
        TOK_OPEN => {
            next_token(s);
            ret = list(s);
            CHECK_NULL(ret);
            if s.type_ != TOK_CLOSE {
                s.type_ = TOK_ERROR;
            } else {
                next_token(s);
            }
        }
        _ => {
            ret = new_expr(0, 0);
            CHECK_NULL(ret);
            s.type_ = TOK_ERROR;
            unsafe {
                (*ret).value = f64::NAN;
            }
        }
    }
    ret
}

fn power(s: &mut State) -> Box<Expr> {
    let mut sign = 1;
    while s.function == ADD || s.function == SUB {
        if s.function == SUB {
            sign = -sign;
        }
        next_token(s);
    }
    let ret: Box<Expr>;
    if sign == 1 {
        ret = base(s);
    } else {
        let b = base(s);
        check_null(Some(b));
        ret = Expr::new_expr(TE_FUNCTION1 | TE_FLAG_PURE, b);
        check_null(Some(ret.clone()));
        ret.function = negate;
    }
    ret
}

fn factor(s: &mut state) -> *mut te_expr {
    let mut ret = power(s);
    CHECK_NULL!(ret);
    while s.tok_type == TOK_INFIX && (s.function as usize == powf as usize) {
        let t = s.function;
        next_token(s);
        let p = power(s);
        CHECK_NULL!(p, te_free(ret));
        let prev = ret;
        ret = NEW_EXPR!(TE_FUNCTION2 | TE_FLAG_PURE, ret, p);
        CHECK_NULL!(ret, te_free(p), te_free(prev));
        unsafe {
            (*ret).function = t;
        }
    }
    ret
}

fn term(s: &mut State) -> TeExpr {
    let mut ret = factor(s);
    check_null(Some(ret.clone()));
    while s.ttype == TokenType::TokInfix
        && matches!(
            s.function,
            Some(TokenFunction::Mul) | Some(TokenFunction::Divide) | Some(TokenFunction::Fmod)
        )
    {
        let t = s.function.unwrap();
        next_token(s);
        let f = factor(s);
        check_null(Some(f.clone()));
        let prev = ret.clone();
        ret = TeExpr::new(Some(t), vec![ret, f]);
        check_null(Some(ret.clone()));
        ret.function = Some(t);
    }
    ret
}

fn expr(s: *mut state) -> *mut te_expr {
    let mut ret = term(s);
    if ret.is_null() {
        return ret;
    }
    while (*s).type_ == TOK_INFIX
        && ((*s).function == add as te_fun2 || (*s).function == sub as te_fun2)
    {
        let t = (*s).function;
        next_token(s);
        let te = term(s);
        if te.is_null() {
            te_free(ret);
            return te;
        }
        let prev = ret;
        ret = NEW_EXPR(TE_FUNCTION2 | TE_FLAG_PURE, ret, te);
        if ret.is_null() {
            te_free(te);
            te_free(prev);
            return ret;
        }
        (*ret).function = t;
    }
    ret
}

fn list(s: &mut State) -> Option<Box<TeExpr>> {
    let mut ret = expr(s)?;
    check_null!(ret);
    while s.token_type == Tok::Sep {
        next_token(s);
        let e = expr(s)?;
        check_null!(e, te_free(ret));
        let prev = ret;
        ret = new_expr(TE_FUNCTION2 | TE_FLAG_PURE, ret, e);
        if ret.is_null() {
            let _ = te_free(e);
            let _ = te_free(prev);
            return None;
        }
        ret.function = comma;
    }
    Some(ret)
}

fn te_eval(n: *const te_expr) -> f64 {
    unsafe {
        if n.is_null() {
            return f64::NAN;
        }
        match TYPE_MASK((*n).type_) {
            TE_CONSTANT => (*n).value,
            TE_VARIABLE => *(*n).bound,
            type_ if ((TE_FUNCTION0..=TE_FUNCTION7).contains(&type_)) => match ARITY((*n).type_) {
                0 => TE_FUN!(()),
                1 => TE_FUN!(f64, M!(0)),
                2 => TE_FUN!(f64, f64, M!(0), M!(1)),
                3 => TE_FUN!(f64, f64, f64, M!(0), M!(1), M!(2)),
                4 => TE_FUN!(f64, f64, f64, f64, M!(0), M!(1), M!(2), M!(3)),
                5 => TE_FUN!(f64, f64, f64, f64, f64, M!(0), M!(1), M!(2), M!(3), M!(4)),
                6 => TE_FUN!(
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    M!(0),
                    M!(1),
                    M!(2),
                    M!(3),
                    M!(4),
                    M!(5)
                ),
                7 => TE_FUN!(
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    M!(0),
                    M!(1),
                    M!(2),
                    M!(3),
                    M!(4),
                    M!(5),
                    M!(6)
                ),
                _ => f64::NAN,
            },
            type_ if ((TE_CLOSURE0..=TE_CLOSURE7).contains(&type_)) => match ARITY((*n).type_) {
                0 => TE_FUN!((*(*n).parameters.add(0))),
                1 => TE_FUN!((*(*n).parameters.add(1), f64, M!(0))),
                2 => TE_FUN!((*(*n).parameters.add(2), f64, f64, M!(0), M!(1))),
                3 => TE_FUN!((*(*n).parameters.add(3), f64, f64, f64, M!(0), M!(1), M!(2))),
                4 => TE_FUN!((
                    *(*n).parameters.add(4),
                    f64,
                    f64,
                    f64,
                    f64,
                    M!(0),
                    M!(1),
                    M!(2),
                    M!(3)
                )),
                5 => TE_FUN!((
                    *(*n).parameters.add(5),
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    M!(0),
                    M!(1),
                    M!(2),
                    M!(3),
                    M!(4)
                )),
                6 => TE_FUN!((
                    *(*n).parameters.add(6),
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    M!(0),
                    M!(1),
                    M!(2),
                    M!(3),
                    M!(4),
                    M!(5)
                )),
                7 => TE_FUN!((
                    *(*n).parameters.add(7),
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    f64,
                    M!(0),
                    M!(1),
                    M!(2),
                    M!(3),
                    M!(4),
                    M!(5),
                    M!(6)
                )),
                _ => f64::NAN,
            },
            _ => f64::NAN,
        }
    }
}

fn optimize(n: &mut te_expr) {
    if n._type == TE_CONSTANT || n._type == TE_VARIABLE {
        return;
    }
    if is_pure(n._type) {
        let arity = arity(n._type);
        let mut known = true;
        for i in 0..arity {
            optimize(&mut n.parameters[i]);
            if n.parameters[i].as_ref().unwrap()._type != TE_CONSTANT {
                known = false;
            }
        }
        if known {
            let value = te_eval(n);
            te_free_parameters(n);
            n._type = TE_CONSTANT;
            n.value = value;
        }
    }
}

fn te_compile(
    expression: *const libc::c_char,
    variables: *const te_variable,
    var_count: libc::c_int,
    error: *mut libc::c_int,
) -> *mut te_expr {
    let mut s = state {
        start: expression,
        next: expression,
        lookup: variables,
        lookup_len: var_count,
        ..Default::default()
    };
    next_token(&mut s);
    let root = list(&mut s);
    if root.is_null() {
        if !error.is_null() {
            *error = -1;
        }
        return std::ptr::null_mut();
    }
    if s.r#type != TOK_END {
        te_free(root);
        if !error.is_null() {
            *error = s.next.offset_from(s.start) as libc::c_int;
            if *error == 0 {
                *error = 1;
            }
        }
        return std::ptr::null_mut();
     } else {
         SomeStruct::optimize(root); // Assume optimize is a static method of SomeStruct
         if !error.is_null() {
            *error = 0;
        }
        return root;
    }
}

fn te_interp(expression: &str, error: &mut i32) -> f64 {
    let c_expression = CString::new(expression).unwrap();
    let n = unsafe { te_compile(c_expression.as_ptr(), ptr::null(), 0, error) };
    let ret;
    if !n.is_null() {
        ret = unsafe { te_eval(n) };
        unsafe { te_free(n) };
    } else {
        ret = f64::NAN;
    }
    ret
}

fn pn(n: &TeExpr, depth: usize) {
    let mut output = String::new();
    write!(&mut output, "{:depth$}", "", depth = depth).unwrap();
    match type_mask(n.expr_type) {
        TE_CONSTANT => write!(&mut output, "{}\n", n.value).unwrap(),
        TE_VARIABLE => write!(&mut output, "bound {:p}\n", n.bound).unwrap(),
        _ => {
            let arity = arity(n.expr_type);
            write!(&mut output, "f{}", arity).unwrap();
            for param in &n.parameters[..arity] {
                write!(&mut output, " {:p}", param).unwrap();
            }
            writeln!(&mut output).unwrap();
            for param in &n.parameters[..arity] {
                pn(param, depth + 1);
            }
         }
     }
     println!("{}", output);
 }

fn te_print(n: &te_expr) {
    pn(n, 0);
}

